Insider Training

Treadmills that make winter miles more bearable.

They ain't cheap, but when daylight slips away and the weather turns nasty, in–house treadmills can literally save your running. We chose three of the newest models and had 20 testers in Boulder, Colorado, put more than 100 miles on each. Here's what we found.

TRUE FITNESS PS800 $3,699

This machine provides the smoothest and most stable running experience of the bunch, making incline and speed changes without any jerking. It's also one of the few treadmills that allow you to adjust the cushioning of the belt, although most of our testers didn't notice a huge difference between its firmest setting and its softest one. Generally, testers liked the quick keys for easy speed and incline changes, but several noted that there wasn't a quick "zero incline" key to bring the angle down.

Tester Says "It felt very solid and silky smooth through my entire run. I really liked all of the workout options."—Chris Lee

If you dread the monotony of treadmill running, the latest Pro VR (upgraded with a more durable deck and belt) offers some much needed variety. Besides the six distance–based courses modeled on famous runs around the country, such as the Tahoe Rim and Appalachian trails, the treadmill features 16 other programmed workouts. It's also one of the few home models capable of a negative incline, which makes it ideal for downhill training. While most testers thought the speed and incline adjustments were smooth, some felt that the frame of this upgrade still shook a bit too much.

Tester Says "The incline transitions were so smooth, I almost didn't notice the deck going up and down."—Kristie Schorer

Fold—up treadmills have gotten a bad rap for being flimsy underfoot, but the deck of the TR21f is rock solid. The steel frame supports up to 400 pounds, and folds up by simply lifting the rear of the deck. Testers liked how the console's numerous speed, incline, and program buttons made on–the–fly adjustments so convenient. Yet while the console is easy to use, the display is frustratingly simple, with distance only measured to a single decimal place (3.2 miles, as opposed to 3.25), and there's no option to show mph instead of per–mile pace.

Tester Says "The panel display clearly shows vital info like speed and distance, and I could easily switch between workouts with one touch."—Deb Nastro

Go Fast: A good rule of thumb for setting the pace and length of speedwork programs: Aim to run your longer intervals (three to eight minutes) just shy of your 10–K pace, and your shorter efforts (one to three minutes) closer to your 5–K pace. Indoor running means wind drag doesn't slow you down as it would outside, so your treadmill times will probably be faster.

Climb Higher: Most runners use less oxygen and have a lower heart rate when training on a treadmill than when they run on the roads, so consider tackling a steeper incline (and even going at a faster pace) during your indoor hill workouts. Don't go overboard though: Climbing a steep incline of 11 to 15 percent is more of a strength-training workout than a running one.

Target Heart Rate: Heart–rate zone programs are ideal for recovery runs because they force you to maintain a steady effort level by automatically speeding up or slowing down the belt when your heart rate gets too low or high.